Electric elevator



(No Model.)

W. BAXTER, Jr. ELECTRIC ELEVATOR.

No. 481,386. Patented Aug. 23, 1892.

UNITED STATES PATENT @FFICE.

WILLIAM BAXTER, JR, OF BALTIMORE COUNTY, MARYLAND.

ELECTRIC ELEVATO R.

SPECIFICATION forming part of Letters Patent No. 481,386, dated August23, 1892.

Application filed July 19, 1888. Renewed October 31, 1890. Serial No.369,873. (No model.)

T0 at whom it may concern.-

Be it known that I, WILLIAM BAXTER, Jr, a citizen of the United States,residing in the ninth election district of the county of Baltimore,State of Maryland, have invented certain new and useful Improvements inSystems of Operating Electric Elevators with Cable- Conductors forConstant Current, fully described and represented in the followingspecification and the accompanying drawing, forming a part of the same.

This invention consists in a particular arrangement of the circuitsconnected with a switch upon the moving car through the medium of aflexible cable, the construction being adapted for a current of constantstrength, and the construction in one form being provided with switchesto stop the car automatically at the top and bottom of the hoistway.

The annexed drawing is a diagram of a hoistway provided with landings,door-frames, and landing-doors, and a hoisting-drum connected with thecar by a rope and rotated by a belt from an electric motor.

In the drawing, M are the field-coils of the motor. B and B are thecommutator-brushes of the same. Tis the car, T the door-frames situatedat the several landings, and T the doors, one of which is shown pushedopen. The cable A, connecting the motor to the car, is shown formed offour conductors a, b, c, and (Z, which are perfectly insulated from oneanother. The motor being series-wound, the positive current from themain-line wire 7 passes through the field-coils and is connected withthe conductor 0. The brushB is connected with the conductor a and thebrush B with the conductor 1), while the conductor d is connected withthe negative linewire S.

The car-switch consists in two pivoted levers 3 and 4:, connected,respectively, with the conductors c and cl. The levers are electricallyconnected when in their normal position, as shown in the drawing, by abar 1, and the entire current is then shunted around the armature,passing from the field-coils of the motor directly to the line-wire 8through the conductors c d and the levers 3 4c. To actuate the motor inopposite directions, the bar is connected with the conductor a, andcontacts 2 at each end of the bar are both connected with the conductor1). The shifting of the switch to the right, as indicated in dottedlines in the drawing, operates then to throw the current from thefield-coils (through the conductor 0 and lever 3) into the contact-stud2, conductor 7), and brush B, the current passing from the oppositebrush through the conductor a, to the bar 1, and thence through thelever 4E and conductor 61 to the line-wire S. The movement of the leversin the opposite direction shifts the lever afrom contact with the barlinto contact with the stud 2 and leads the current into the brush B,from whence it passes through the armature, and from the brush B throughthe lever 4: to the line-wire S. I

It will be seen from the above description that the motor may be stoppedor caused to rotate in either direction by a proper movement of theswitch-levers, and that the hoisting mechanism (shown connected directlywith a pulley upon the motor-armature by means of the belt 1) would becorrespondingly affected and the car caused to ascend or descend or tostop, according to the movement of the switch.

It is immaterial what form of switch be placed upon the car, as variousforms of switches are already well known for performing the samefunctions.

Another shunt-circuitis shown in the drawing for the insertion ofswitches to stop the car automatically at the top and bottom of thehoistway by stopping the electric motor or affecting the electriccircuit in any equivalent manner. The lines 7t represent theshunt-circuit connecting the line-wires 7 and S, and y are switches heldnormally open in the said circuit by springs 1 The switches are shownprovided with arms 11 and wedges g are provided upon the car T to movesuch switches in opposition to the springs 1 and to thus close thecircuit when the car has reached the limit of its travel. By means ofsuch switches any accident may be prevented arising from negligence onthe part of the operator when the car is at either end of the hoistway.Then the car is stopped by the operation of the switch y, the circuitsthrough the car or landing switches would be inoperative until theshunt-circuit was opened, for which purpose hand-switches a; areprovided within the reach of the operator when the car is thus stopped,the opening of which would break the shunt-circuit and cause the currentto flow in the proper course through the car or landing switches.

The drawing represents circuits adapted for a current of constantstrength, in which case the switches y would be held normally open. Theswitches a: would in such case be held normally shut and would then beclosed automatically as soon as the operators hand was withdrawn.

Having thus set forth my invention, whatI claim herein, and desire tosecure by Letters Patent, is

1. In an electric-elevator system adapted to a current of constantstrength, the combination, with the moving car, of an electric motorwound in series, four insulated electric conductors iuclosed in aflexible cable, having one end attached to the car, a switch upon thecar, having contacts connected, respectively, with thecommutator-brushes of the motor, one of the terminals of the fieldcoils,and one pole of the generator, and a movable connector in the saidswitch adapted to vary the course of the current through the motor andto thereby vary the movements of the hoisting mechanism, as and for thepurpose set forth.

2. In an electric-elevator system in which a car or platform hoistingdevice is operated by a stationary electric motor, the combination, withthe electric motor and the car or platform moved thereby, of anoperative electric circuit adapted for a current of constant strength, aswitch in said circuit adapted to vary the course of the current in themotor to vary the movement of the hoisting mechanism, one or moreshunt-circuits around the motor, normally-open switches placed in suchshunt-circuits, suitable mechanism actuated by the car at the end of itstravel to move such switches and thereby short-circuit the motor, andhand-switches adapted to reopen such shuntcircuit or circuits to restorethe current to the operative circuits, substantially as herein setforth.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

WILLIAM BAXTER, JR. Witnesses:

L. LEE, THos. S. CRANE.

